For atoms to bond with each other, they need to share their electrons. This tendency of an atom to attract bonding pairs of electrons is measured using electronegativity. It is the ability of an atom to attract electrons to itself in a covalent bond. It is affected by the atomic number of an element and the distance of the outermost shell from the nucleus. The most common scale used to measure electronegativity is the Pauling scale. The most electronegative atom in the periodic table is fluorine followed by oxygen, and the least electronegative atoms are cesium and francium. Let us look at some information related to electronegativity bonds.
Electronegativity was first discovered by Linus Pauling in the year 1932. He got the idea of electronegativity using the Valance Bond Theory. This theory helped him realize the relationship of one chemical element with another element. It is not possible to measure electronegativity of an element directly as it depends on the properties of an element.
Electronegativity is basically the property of an element that helps in attracting a pair of electrons or a single electron towards it. He came up with Pauling scale, which is the simplest way to calculate electronegativity of an element in the Periodic Table. The trends show that the electronegativity of an atom or element is directly related to its atomic number or the space between valance electrons and nucleus. It has been found that the difference in electronegativity chart varies with the environment of the element. The electronegativity bond is based on the molecule having polar covalent bond. Simply put, atoms that have high electonegativity will attract more electrons or may even attract all the electrons from an atom. Atoms having low electronegativity tend to share the most electrons, and may even end up losing all their electrons.
Electronegativity Chart for Periodic Table
The above electronegativity chart shows that the measure of attraction between an atom for electrons in a chemical bond is electronegativity.
When the atom shows higher electronegativity, it is better able to attract bonding electrons. Ionization energy is related to electronegativity as low ionization electrons exhibit low electronegativity. This is because their nuclei does not have a strong attractive force on electrons. When you refer to a decreasing electronegativity, you will find that electronegativity decreases as atomic number increases. This is because of the distance between valance electrons and nucleus.
There are particular electronegativity trends that are seen in the Periodic Table. When one moves left to right in the Periodic Table, the atomic radius of the elements decreases, ionization energy increases, and electronegativity increases. When one moves from top to bottom, the atomic radius increases, the ionization energy decreases, and the electronegativity too decreases.
You may have noticed in the above chart that noble gases do not have any electronegativity as they generally do not bond. This is because their outer shell is full with eight electrons, leaving them with very little tendency to participate in chemical reactions.